Patent attributes
The present invention provides a scheme for compressing and decompressing the depth, or Z, components of image data. Image data is grouped into a plurality of tiles. A test is performed to determine if a tile can be compressed so that its size after compression is less than its size before compression. If so, the tile is compressed. A tile table includes a flag that can be set for each tile that is compressed. In one scheme, each tile comprises a 4×4 block of pixels. For each pixel, the visible depth complexity is determined where each visible level of depth complexity is represented by a plane equation. Depending on the depth complexity, a compression scheme is chosen that stores multiple plane equations in cache lines. The compression scheme can be used with unsampled or multisampled data and provides higher levels of compression in multisampled environments.
